scholarly journals Scenarios and Pathways of Radionuclide Releases from Near-Surface Waste Disposal Facilities: A Brief Overview of Historical Evidence

2020 ◽  
pp. 21-27
Author(s):  
D. Bugai ◽  
R. Avila
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Safety Assessment ◽  
Historical Evidence ◽  
Nuclear Facilities ◽  
Near Surface ◽  
Soil Covers ◽  
Low Level ◽  
Radionuclide Release ◽  
Early Degradation

The very low-level waste (VLLW) produced during decommissioning of nuclear facilities can be suitable for disposal in landfill type facilities. Considering the similarities in design, the experience gained in near-surface disposal of radioactive waste in trenches and vaults is relevant to the issue of VLLW disposal in landfills. This paper presents a brief review of internationally reported cases of radionuclide releases from near-surface disposal facilities. Based on this review, the conclusions are made that the following radionuclide release and exposure scenarios should be accounted for in safety assessment of VLLW disposal in landfills: i) leaching from waste to groundwater by atmospheric precipitations; ii) bath-tubing scenario; iii) scenarios caused by extreme meteorological and hydrological events (erosion, flooding, etc.); iv) human intrusion. The gaseous transport deserves attention for a number of relevant radionuclides, such as (C-14, Rn-222, etc.). In addition, the possibility of early degradation of engineered containment structures (soil covers, bottom seals) should be cautiously considered.

Discussion on Very Low-Level Radioactive Waste near Surface Disposal

2013 ◽  
Vol 807-809 ◽  
pp. 1207-1210 ◽  
Author(s):  
Hai Ying Chen ◽  
Chun Ming Zhang ◽  
Shao Wei Wang ◽  
Qiao Feng Liu ◽  
Jing Ru Han
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Early Period ◽  
Radioactive Waste Disposal ◽  
Nuclear Facilities ◽  
Near Surface ◽  
Barrier Materials ◽  
Low Level ◽  
Low Level Radioactive Waste ◽  
Natural Barriers

Radioactive waste disposal is one of the most sensitive environmental problems. As the arriving of decommissioning of early period nuclear facilities in China, large amounts of very low-level radioactive waste will be produced inevitably. The domestic and abroad definitions about very low-level radioactive waste and its disposal were introduced, and then siting principles of near surface disposal of very low-level radioactive waste were discussed. The near surface disposal sites’ natural barriers were analyzed from the crustal structure and the radionuclide adsorption characteristics of natural barriers. The near surface disposal sites’ engineering barriers were analyzed from the repository design and the repository barrier materials selection. Finally, the improving direction of very low-level radioactive waste disposal was proposed, which would promote the study of very low-level radioactive waste disposal in China.

A Summary of Radiological Waste Disposal Practices in the United States and the United Kingdom

2009 ◽  
Author(s):  
Victoria M. Maranville ◽  
Richard McGrath
Keyword(s):  
United States ◽  
Radioactive Waste ◽  
Public Participation ◽  
Case Studies ◽  
Waste Disposal ◽  
The United States ◽  
Near Surface ◽  
Low Level ◽  
The Us ◽  
The Uk

A systematic review of near-surface repositories for radioactive waste in the United States (US) was conducted. The main focus of the review consisted of a literature search of available documents and other published sources on low level radioactive waste (LLRW) disposal practices, remediation of LLRW sites in the US, and public participation for remediation efforts of near-surface radiological waste disposal sites in the US. This review was undertaken to provide background information in support of work by the United Kingdom’s (UK) Low Level Waste Repository (LLWR) and to aid in optimizing the future management of this site. The review contained a summary of the US and UK radiological waste classification requirements including a discussion of the waste types, disposal requirements, and the differences between US and UK disposal practices. A regulatory overview and evolution of regulatory requirements in the US is presented. The UK regulatory environment is also discussed and contrasted to the US process. The public participation, as part of the US regulatory process, is provided and the mechanism for stakeholder identification and involvement is detailed. To demonstrate how remediation of radiologically impacted sites is implemented in the US, existing US case studies, in which remediation activities were carried out, were reviewed. The following information was compiled: type of wastes disposed of to US shallow ground facilities [with comparison with UK classifications], facility designs (with special emphasis on those directly comparable to the subsurface conditions in the UK), and deficiencies identified in operation or in demonstrating safe post closure; and processes and difficulties in remedial actions encountered at the selected sites. Stakeholder involvement is discussed within the case studies. Publicly available information related to radiological waste management and disposal practices were reviewed. Two sites are presented in this publication for discussion. These US sites were selected based on the site similarities to conditions in the UK.

Influence of Cracks in Cementitious Engineered Barriers in a Near-Surface Disposal System: Assessment Analysis of the Belgian Case

2013 ◽  
Author(s):  
Janez Perko ◽  
Suresh C. Seetharam ◽  
Diederik Jacques ◽  
Dirk Mallants ◽  
Wim Cool ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Total System ◽  
Near Surface ◽  
Disposal Facility ◽  
The Matrix ◽  
Flow Through ◽  
System Assessment ◽  
Engineered Barriers ◽  
Radionuclide Release

In large cement-based structures such as a near surface disposal facility for radioactive waste voids and cracks are inevitable. However, the pattern and nature of cracks are very difficult to predict reliably. Cracks facilitate preferential water flow through the facility because their saturated hydraulic conductivity is generally higher than the conductivity of the cementitious matrix. Moreover, sorption within the crack is expected to be lower than in the matrix and hence cracks in engineered barriers can act as a bypass for radionuclides. Consequently, understanding the effects of crack characteristics on contaminant fluxes from the facility is of utmost importance in a safety assessment. In this paper we numerically studied radionuclide leaching from a crack-containing cementitious containment system. First, the effect of cracks on radionuclide fluxes is assessed for a single repository component which contains a radionuclide source (i.e. conditioned radwaste). These analyses reveal the influence of cracks on radionuclide release from the source. The second set of calculations deals with the safety assessment results for the planned near-surface disposal facility for low-level radioactive waste in Dessel (Belgium); our focus is on the analysis of total system behaviour in regards to release of radionuclide fluxes from the facility. Simulation results are interpreted through a complementary safety indicator (radiotoxicity flux). We discuss the possible consequences from different scenarios of cracks and voids.

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